I think we all become so many other things that we forget how to be ourselves don't we? We become Mrs so and so or Mr X's partner, then we become so and so's mum and then someone else's mum and eventually we are all these other things and we don't actually have time to be LisaR or the real BeauSoleil. The longer we are the other things means that actually the real us seems a little bit alien when we do find time to become 'us' again!! Does this make sense? I hope so because all that you said made true sense to me.
As optimistic said it's quite easy to believe that others are confident when it's highly likely they re feeling just like you!! (and me!)